Double-pane window structures have been proposed in a variety of constructions for acoustic and thermal installation purposes. Such structures have generally comprised two glass panes held in a predetermined spaced relationship by frame-like or other spacer structures extending around the peripheries of the panes and defining the peripheral edges of the window. The double-pane structure has an evacuated or gas-containing space between the sheets of glass while the frame is of low thermal conductivity so that conduction through the window of heat and sound is minimized.
It has been proposed to provide one or both of the panes in such structures of double-sheet construction whereby the window may consist of a pair of outer panes or glass sheets and at least one inner pane or glass sheet received between the outer panes.
In a preferred construction, a pair of inner glass sheets or panes is provided between the outer panes and complex structures are employed to space the several panes apart. For example, in prior-art systems and in the present system, it is desirable to provide a pair of inner panes or glass sheets having a relatively large spacing of, say 5 to 25 mm and a pair of outer glass sheets or panes, flanking the inner panes and spaced from the respective inner panes by relatively small distances of, say 0.3 to 2.0 mm, preferably 0.5 mm.
To assemble these window structures, it has been proposed to provide an outer spacer defining the distance between the outer panes and a pair of inner spacers individually inserted to space each inner pane from the proximal outer pane. These systems are complex to assemble and frequently do not provide satisfactory positioning of the panes relative to one another. For example, the spacing between the inner panes may not be adequately fixed.